Heretofore, in order to reduce automobile body weight, a steel plate for automobile body is generally processed to a thin plate of 0.6 to 0.8 mm thick. Therefore, it is known that the body steel plate is attempted to be reinforced by sticking a steel plate-reinforcing sheet onto inner side of the steel plate.
Such steel plate-reinforcing sheet is, for example, stuck during an assembly step of the body steel plate and then heated to foam with the heat supplied during elecrodeposition coating to achieve reinforcement. For example, there is proposed a steel plate-reinforcing sheet wherein a foaming resin layer is laminated onto a backing (for example, cf. JP-A-7-68695).
Moreover, since the body steel plate is a thin plate, a vibration sound generates while moving and noise may be generated at door opening and closure. Therefore, in order to prevent the generation of these vibration sound and noise, there is proposed a damping sheet wherein a rubber composition is laminated onto a backing (for example, cf. JP-A-9-123356).